1. Field of The Invention
The present invention relates generally to personal image display apparatus which permit monitoring of an image, such as a video or television image, in an immediate form via a pair of ocular lenses. Particularly, the present invention relate to an automatic image regulating arrangment for such a personal viewing apparatus so as to provide optimal visibility under different ambient light conditions.
2.Description of The Related Art
Recently, head mounted personal viewers utilizing a display element such as an LCD (liquid crystal display) provided with a backlighting arrangement and a reflective element such as a mirror to reflect the displayed image to the eyes of a viewer, have been disclosed. By utilizing for example, a convex lens for viewing and providing a concave mirror, a large image area can be provided from a relatively small display element, thus allowing the apparatus to be more effective, as well as more compact.
In such head mounted image display devices, it is necessary to reduce or interrupt intrusion of surrounding ambient light for maximizing image visibility within the goggles, helmet etc., especially if used outdoors or the like. Commonly, in outdoor use, when surrounding ambient light is too bright, the displayed image becomes difficult to see, this may become a potential danger when the image display is viewed in conjunction with another activity.
Thus it has been required to provide a personal view arrangment in which the safety of use in conditions such as described above is enhanced, while the visibility of the displayed image is maximized for allowing the viewer to sufficiently concentrate on the program (viewing) material.
`Virtual reality` related devices have been developed by various manufacturers. Numerous types of personal viewing arrangements, including head-mounted image display devices have been disclosed which allow private viewing of program material, such as games, movies, simulations etc. Usually such a personal viewing apparatus is enclosed in a helmet or goggle type arrangement. Some disclose a head mounted image display arrangement in which a pair of LCD display panels are disposed at right and left sides of the headset (helmet, etc.) for providing images to the right and left eyes of the user. Referring now to FIGS. 10(a) and 10(b), an image adjustment method of such a conventional personal viewing device will be explained in detail.
As may be seen, an identical image is displayed on a left LCD 53L and a right LCD 53R, the alignment between the images is offset by a horizontal amount `a` and by a vertical amount `b`. According to the conventional method, means are provided to move the positioning of at least one on the left or right LCDs in horizontal and vertical directions for converging the images on the left and right LCDs to form a single image, as shown in FIG. 10(b). According to this construction, in order to protect image quality from impingement from outside light, it is necessary to make the LCDs quite large and or provide complete shading for the eye in order to completely block leakage of outside light in the the viewpath. However, such measures lead to a large and more costly device. Also, in a situation where it is desirable that a certain amount of outside ambient light be perceivable, the above situation is not advantageous since it attempts to prevent any penetration of ambient light.
Also, since such a personal viewer is likely to be used in various locations or environments, each having potentially different ambient light levels, being in sunlight, incandescent light, fluorescent light etc. According to these differing ambient light sources, a white balance of images displayed in such different environments may be effected making it difficult to consistently display a correct colour balance for providing realistic colour to the display material.
Another problem which may be encountered in such personal display devices can be misplacement of one or more of the LCDs during manufacture, in such a case it may be impossible to adjust the displayed image to enable suitable viewing by the user.
Thus it has been required to provide a image regulating arrangement for a personal image display device which will solve the above problems while allowing the device to remain compact. Also the present invention provides for individual adjustment of both displays so as to provide suitable image adjustment for all users.